Making a Firefox Extension Work Offline — Service Workers vs. Cache API A common question when building browser extensions: how do you handle offline or spotty network conditions? Here is what I learned building the Weather & Clock Dashboard . The Problem The extension fetches weather data from an external API. If the user opens a new tab with no internet connection, they should see the last known weather, not an error. Option 1: Service Workers Service workers can intercept network requests and serve cached responses. But in MV3 Firefox extensions, service workers have limitations — they are not persistent and can be terminated.…